Recent concern about the safety of carbon fibers has led to a program to develop silicon carbide-silicon nitride fibers, generally of the formula Si.sub.x N.sub.y C.sub.z. Current use of carbon fibers as reinforcement in composite materials has been suggested to be potentially unsafe due to the high electrical conductivity of carbon. Si.sub.x N.sub.y C.sub.z fibers are 10.sup.6 times more electrically resistive than carbon fibers, and at the same time have similar mechanical properties. Si.sub.x N.sub.y C.sub.z fibers are produced from the monomer tris (N-methylamino) methylsilane, which for convenience is referred to as TNMAMS.
The preparation of TNMAMS is disclosed in German Patent Disclosure No. 2,218,960, dated Nov. 8, 1973, in which Dr. Wolfgang Verbeek is listed as the inventor. In Verbeek, a process for producing materials from homogeneous mixtures of silicon carbide and silicon nitride is disclosed. The reaction between methyltrichlorosilane and methylamine is disclosed as an example of the general reaction of converting halogen substituted silanes with one or more compounds having NH.sub.2 or NH groups. Example 1 of Verbeek teaches the addition of methylamine to a solution of methyltrichlorosilane dissolved in petroleum ether for reaction at 40.degree. C. After purification by distillation, the product is used to manufacture a resin. Example 2 teaches the use of another silane to which is added methylamine for reaction at 40.degree. C., with purification in the same manner. Verbeek is silent about the yield of monomer.
Aliphatic chlorosilanes are also reacted with large excesses of gaseous ammonia in U.S. Pat. No. 2,579,416, to N. D. Cheronis, under anhydrous conditions. Additionally, U.S. Pat. No. 2,579,417, also to Cheronis discloses the use of a gaseous primary amine, in excess, in a similar reaction. Reaction temperatures for both Cheronis references are between -10.degree. C. and -15.degree. C. In U.S. Pat. No. 4,255,549 to Christophliemke et al, a reaction of methyltrichlorosilane with a great excess of ammonia is taught, where the reaction is accomplished at above 0.degree. C. under pressure. Christophliemke et al is stated to be an improvement on the Cheronis work. Other patents teach the reaction of organohalosilane at temperatures above 0.degree. C., such as Johannson, U.S. Pat. No. 2,429,883; Breedervald et al, U.S. Pat. No. 2,807,635; Takamizawa et al, U.S. Pat. No. 3,927,057; and Berger et al, U.S. Pat. No. 3,700,716.
Efforts to produce a significant quantity of TNMAMS which is suitable for use in the production of useful resins has not been possible using the methods described in the prior art. Several of these references teach the production of laboratory quantities of polymerizable monomers, but none provide a process which can produce large quantities of monomer of high yield and suitable purity. Scale-up of these prior art methods leads to substantial difficulties such as poor yields, difficult purification, loss of reactants and wasted by-products.